Departments of Anesthesiology, Stony Brook University School of Medicine, Stony Brook, New York 11794, USA.
Am J Physiol Heart Circ Physiol. 2011 Mar;300(3):H922-30. doi: 10.1152/ajpheart.00860.2010. Epub 2011 Jan 7.
It is well established that inhibition of glycogen synthase kinase (GSK)-3β in the young adult myocardium protects against ischemia-reperfusion (I/R) injury through inhibition of mitochondrial permeability transition pore (mPTP) opening. Here, we investigated age-associated differences in the ability of GSK-3β inhibitor [SB-216763 (SB)] to protect the heart and to modulate mPTP opening during I/R injury. Fischer 344 male rats were assigned from their respective young or old age groups. Animals were subjected to 30 min ischemia following 120 min reperfusion to determine myocardial infarction (MI) size in vivo. Ischemic tissues were collected 10 min after reperfusion for nicotinamide adenine dinucleotide (NAD(+)) measurements and immunoblotting. In parallel experiments, ventricular myocytes isolated from young or old rats were exposed to oxidative stress through generation of reactive oxygen species (ROS), and mPTP opening times were measured by using confocal microscopy. Our results showed that SB decreased MI in young SB-treated rats compared with young untreated I/R animals, whereas SB failed to significantly affect MI in the old animals. SB also significantly increased GSK-3β phosphorylation in young rats, but phosphorylation levels were already highly elevated in old control groups. There were no significant differences observed between SB-treated and untreated old animals. NAD(+) levels were better maintained in young SB-treated animals compared with the young untreated group during I/R, but this relative improvement was not observed in old animals. SB also significantly prolonged the time to mPTP opening induced by ROS in young cardiomyocytes, but not in aged cardiomyocytes. These results demonstrate that this GSK-3β inhibitor fails to protect the aged myocardium in response to I/R injury or prevent mPTP opening following a rise in ROS and suggest that healthy aging alters mPTP regulation by GSK-3β.
已有充分证据表明，在年轻成年心肌中抑制糖原合酶激酶（GSK）-3β可通过抑制线粒体通透性转换孔（mPTP）开放来防止缺血再灌注（I/R）损伤。在此，我们研究了 GSK-3β抑制剂[SB-216763（SB）]在保护心脏和调节 I/R 损伤期间 mPTP 开放方面的能力在年龄相关差异。将 Fischer 344 雄性大鼠从各自的年轻或老年组中分配出来。动物接受 30 分钟缺血，随后进行 120 分钟再灌注，以确定体内心肌梗死（MI）的大小。再灌注 10 分钟后收集缺血组织，用于烟酰胺腺嘌呤二核苷酸（NAD（+））测量和免疫印迹。在平行实验中，将来自年轻或老年大鼠的心室肌细胞暴露于活性氧（ROS）产生的氧化应激下，并通过共聚焦显微镜测量 mPTP 开放时间。我们的结果表明，与年轻未处理 I/R 动物相比，SB 降低了年轻 SB 处理大鼠的 MI，但 SB 未能显着影响老年动物的 MI。SB 还显着增加了年轻大鼠中 GSK-3β的磷酸化，但在老年对照组中磷酸化水平已经很高。在 SB 处理和未处理的老年动物之间未观察到显着差异。与年轻未处理组相比，SB 处理的年轻动物的 NAD（+）水平在 I/R 期间得到更好的维持，但在老年动物中未观察到这种相对改善。SB 还显着延长了年轻心肌细胞中 ROS 诱导的 mPTP 开放时间，但不能延长老年心肌细胞的 mPTP 开放时间。这些结果表明，这种 GSK-3β 抑制剂不能保护衰老的心肌免受 I/R 损伤，也不能防止 ROS 升高后 mPTP 的开放，并表明健康衰老改变了 mPTP 通过 GSK-3β 的调节。
